The present invention was conceived in the context of central tyre inflation systems (CTISs). CTISs were originally developed for military applications, in particular for military applications concerning off-road military wheeled trucks and trailers. However, CTISs are nowadays incorporated into non-military vehicles such as specialist construction equipment and some agricultural vehicles.
A CTIS typically comprises one or more compressed air sources located on-board the vehicle and connected to one or more tyres. Tyre pressure can therefore be adjusted by operating the CTIS. Typically, a CTIS provides for delivery of compressed air to a tyre supply line. In some examples, a portion of the tyre supply line is integrated into a vehicle axle. Some axles comprise articulated joints formed by a driveshaft and a stub axle connected to form a constant velocity (CV) joint, and the tyre supply line extends through the CV joint. The CV joint is typically protected by a CV joint gaiter. An enclosure defined by the CV joint and the CV joint gaiter accommodates the bearing surfaces of the CV joint and a volume of a suitable lubricant such as grease with which to lubricate said bearing surfaces. This enclosure is known as the CV joint enclosure.
Air supplied through the CV joint to inflate or deflate the tyre may leak into the CV joint enclosure and thus inflate the gaiter. This is not desirable, and there is accordingly a need to prevent inflation of the gaiter.
As the CV joint enclosure accommodates grease to lubricate and protect moving parts, if an air permeable gaiter material was used as a replacement for a conventional gaiter material, grease deposits would be likely to prevent release of any pressure built up in the gaiter.
EP 2,007,500 B1 discloses a vent for an enclosure containing lubricated machinery.
U.S. Pat. No. 8,075,669 B2 discloses a gas-permeable oleophobic venting material.
WO 2010/039244 A1 discloses a clamping assembly for venting an enclosure having openings extending from the inside of the enclosure to the outside of the enclosure. A gas-permeable liquid-impermeable venting element is disposed to cover at least one hole in a band portion of the venting device. The at least one hole is at least partially aligned with an opening of the enclosure.
It is against this background that the present invention has been conceived. In at least certain embodiments, the present invention seeks to address shortcomings associated with the prior art or to improve parts, components, apparatus, systems and methods disclosed in the prior art.